Restricted range size brings about noteworthy genetic consequences that may affect the viability of a population and eventually its extinction. Particularly, the question if an increase in inbreeding can avert the accumulation of genetic load via purging is hotly debated in the conservation genetic field. Insular populations with limited range sizes represent an ideal setup for relating range size to these genetic factors. Leveraging a set of eight differently sized populations of Galápagos mockingbirds (Mimus), we investigated how island size shaped effective population size (Ne), inbreeding and genetic load. We assembled a genome of M. melanotis and genotyped three individuals per population by whole-genome resequencing. Demographic inference showed that the Ne of most populations remained high after the colonisation of the archipelago 1-2 Mya. Ne decline in M. parvulus happened only 10-20 Kya, whereas the critically endangered M. trifasciatus showed a longer history of reduced Ne. Despite these historical fluctuations, the current island size determines Ne in a linear fashion. In contrast, significant inbreeding coefficients, derived from runs of homozygosity, were identified only in the four smallest populations. The index of additive genetic load suggested purging in M. parvulus, where the smallest populations showed the lowest load. By contrast, M. trifasciatus carried the highest genetic load, possibly due to a recent rapid bottleneck. Overall, our study demonstrates a complex effect of demography on inbreeding and genetic load, providing implications in conservation genetics in general and in a conservation project of M. trifasciatus in particular.
- Klíčová slova
- conservation genetics, demographic inference, genetic diversity, genetic load,
- MeSH
- genetická zátěž * MeSH
- genom * MeSH
- genotyp MeSH
- hustota populace MeSH
- inbreeding * MeSH
- ostrovy MeSH
- Passeriformes * genetika MeSH
- populační genetika * MeSH
- zachování přírodních zdrojů MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Ekvádor MeSH
- ostrovy MeSH
Polyploidy, the result of whole genome duplication (WGD), is widespread across the tree of life and is often associated with speciation and adaptability. It is thought that adaptation in autopolyploids (within-species polyploids) may be facilitated by increased access to genetic variation. This variation may be sourced from gene flow with sister diploids and new access to other tetraploid lineages, as well as from increased mutational targets provided by doubled DNA content. Here, we deconstruct in detail the origins of haplotypes displaying the strongest selection signals in established, successful autopolyploids, Arabidopsis lyrata and Arabidopsis arenosa. We see strong signatures of selection in 17 genes implied in meiosis, cell cycle, and transcription across all four autotetraploid lineages present in our expanded sampling of 983 sequenced genomes. Most prominent in our results is the finding that the tetraploid-characteristic haplotypes with the most robust signals of selection were completely absent in all diploid sisters. In contrast, the fine-scaled variant 'mosaics' in the tetraploids originated from highly diverse evolutionary sources. These include widespread novel reassortments of trans-specific polymorphism from diploids, new mutations, and tetraploid-specific inter-species hybridization-a pattern that is in line with the broad-scale acquisition and reshuffling of potentially adaptive variation in tetraploids.
This article introduces a network data set on the friendships and group work interactions among a convenience sample of 276 Czech Grade 6 students from twelve classrooms, supported by student-level demographic, literacy, motivation, and classroom communication data. Gathered longitudinally at the beginning and end of the 2021/2022 school year, the data provide a relational insight into the nature and evolution of early adolescents' friendships. Moreover, the data provide a unique relational and temporal insight into the verbal interaction of students during classroom group work. This dataset constitutes a valuable resource for educational researchers interested in studying classroom group work as well as for social network scientists studying dynamic social networks.
- Klíčová slova
- Classroom group work, Classroom interaction, Dynamic social network analysis, Peer relationships, School networks, Social network analysis,
- Publikační typ
- časopisecké články MeSH
This chapter outlines an empirical analysis of genome-wide single-nucleotide polymorphism (SNP) variation and its underlying drivers among multiple natural populations within a diploid-autopolyploid species. The aim is to reconstruct the genetic structure among natural populations of varying ploidy and infer footprints of selection in these populations, framed around specific questions that are typically encountered when analyzing a mixed-ploidy data set,e.g., addressing the relevance of natural whole-genome duplication for speciation and adaptation. We briefly review the options for the analysis of polyploid population genomic data involving variant calling, population structure, demographic history inference, and selection scanning approaches. Further, we provide suggestions for methods and associated software, possible caveats, and examples of their application to mixed-ploidy and autopolyploid data sets.
- Klíčová slova
- Arabidopsis, Autopolyploidy, Genetic variation, Population differentiation, Selection scans,
- MeSH
- aklimatizace MeSH
- diploidie * MeSH
- genomika MeSH
- metagenomika * MeSH
- ploidie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The interactions of evolutionary forces are difficult to analyse in free-living populations. However, when properly understood, they provide valuable insights into evolutionary biology and conservation genetics. This is particularly important for the interplay of genetic drift and natural selection in immune genes that confer resistance to disease. The Galápagos Islands are inhabited by four closely related species of mockingbirds (Mimus spp.). We used 12 different-sized populations of Galápagos mockingbirds and one population of their continental relative northern mockingbird (Mimus polyglottos) to study the effects of genetic drift on the molecular evolution of immune genes, the Toll-like receptors (TLRs: TLR1B, TLR4 and TLR15). We found that neutral genetic diversity was positively correlated with island size, indicating an important effect of genetic drift. However, for TLR1B and TLR4, there was little correlation between functional (e.g., protein) diversity and island size, and protein structural properties were largely conserved, indicating only a limited effect of genetic drift on molecular phenotype. By contrast, TLR15 was less conserved and even its putative functional polymorphism correlated with island size. The patterns observed for the three genes suggest that genetic drift does not necessarily dominate selection even in relatively small populations, but that the final outcome depends on the degree of selection constraint that is specific for each TLR locus.
- Klíčová slova
- conservation genetics, innate immunity, island birds, molecular phenotype, purifying selection,
- MeSH
- genetický drift MeSH
- hustota populace MeSH
- Passeriformes * genetika MeSH
- populační genetika MeSH
- selekce (genetika) MeSH
- toll-like receptor 4 * genetika MeSH
- toll-like receptory genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- toll-like receptor 4 * MeSH
- toll-like receptory MeSH
Polymeric materials play a vital role in our daily life, but the growing concern for the environment demands economical and natural biopolymers that can be cross-linked to create technologically innovative lightweight materials. Their cellular matrix with extreme flexibility makes them highly acceptable for application prospects in material science, engineering, and biomedical applications. Furthermore, their biocompatibility, mechanical properties, and structural diversity provide a gateway to research them to form technologically important materials. In the light of the same, the review covers cellulose derivatives. The first section of the study covers the general properties and applications of cellulose and its derivatives. Then, the biopolymers are characterised based on their dielectric properties, crystallinity, rheology, and mechanical properties. An in-depth analysis of the diffuse process of swelling and dissolution followed by a brief discussion on diffusion and diffusion of crosslinking has been done. The review also covers a section on swelling and swelling kinetics of carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC). The examination of all the aforementioned parameters gives an insight into the future aspects of the biopolymers. Lastly, the study briefly covers some preferred choices of cross-linking agents and their effect on the biopolymers.
- Klíčová slova
- Biopolymers, Crosslinking, Diffusion coefficient, Hydrogel swelling, Thermodynamics,
- MeSH
- biopolymery chemie MeSH
- celulosa * chemie MeSH
- hydrogely chemie MeSH
- reologie MeSH
- sodná sůl karboxymethylcelulosy * chemie MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- biopolymery MeSH
- celulosa * MeSH
- hydrogely MeSH
- sodná sůl karboxymethylcelulosy * MeSH
High specific surface area (SSA), porous structure, and suitable technological characteristics (flow, compressibility) predetermine powder carriers to be used in pharmaceutical technology, especially in the formulation of liquisolid systems (LSS) and solid self-emulsifying delivery systems (s-SEDDS). Besides widely used microcrystalline cellulose, other promising materials include magnesium aluminometasilicates, mesoporous silicates, and silica aerogels. Clay minerals with laminar or fibrous internal structures also provide suitable properties for liquid drug incorporation. This work aimed at a comparison of 14 carriers' main properties. Cellulose derivatives, silica, silicates, and clay minerals were evaluated for flow properties, shear cell experiments, SSA, hygroscopicity, pH, particle size, and SEM. The most promising materials were magnesium aluminometasilicates, specifically Neusilin® US2, due to its proper flow, large SSA, etc. Innovative materials such as FujiSil® or Syloid® XDP 3050 were for their properties evaluated as suitable. The obtained data can help choose a suitable carrier for formulations where the liquid phase is incorporated into the solid dosage form. All measurements were conducted by the same methodology and under the same conditions, allowing a seamless comparison of property evaluation between carriers, for which available company or scientific sources do not qualify due to different measurements, conditions, instrumentation, etc.
- Klíčová slova
- adsorption, aluminometasilicates, liquisolid systems, pharmaceutical technology, powder carriers, solid dosage form,
- Publikační typ
- časopisecké články MeSH
Eco-friendly, electrochemically active electrode materials based on covalent graphene derivatives offer enormous potential for energy storage applications. However, covalent grafting of functional groups onto the graphene surface is challenging due to its low reactivity. Here, fluorographene chemistry was employed to graft an arginine moiety via its guanidine group homogeneously on both sides of graphene. By tuning the reaction conditions and adding a non-toxic pore-forming agent, an optimum degree of functionalization and hierarchical porosity was achieved in the material. This tripled the specific surface area and yielded a high capacitance value of approximately 390 F g-1 at a current density of 0.25 A g-1 . The applicability of the electrode material was investigated under typical operating conditions by testing an assembled supercapacitor device for up to 30000 charging/discharging cycles, revealing capacitance retention of 82.3 %. This work enables the preparation of graphene derivatives with covalently grafted amino acids for technologically important applications, such as supercapacitor-based energy storage.
- Klíčová slova
- arginine, fluorographene, graphene, supercapacitor, ultracapacitor,
- Publikační typ
- časopisecké články MeSH
Relative contributions of pre-existing vs de novo genomic variation to adaptation are poorly understood, especially in polyploid organisms. We assess this in high resolution using autotetraploid Arabidopsis arenosa, which repeatedly adapted to toxic serpentine soils that exhibit skewed elemental profiles. Leveraging a fivefold replicated serpentine invasion, we assess selection on SNPs and structural variants (TEs) in 78 resequenced individuals and discover significant parallelism in candidate genes involved in ion homeostasis. We further model parallel selection and infer repeated sweeps on a shared pool of variants in nearly all these loci, supporting theoretical expectations. A single striking exception is represented by TWO PORE CHANNEL 1, which exhibits convergent evolution from independent de novo mutations at an identical, otherwise conserved site at the calcium channel selectivity gate. Taken together, this suggests that polyploid populations can rapidly adapt to environmental extremes, calling on both pre-existing variation and novel polymorphisms.
- MeSH
- alely * MeSH
- Arabidopsis účinky léků genetika MeSH
- fyziologická adaptace účinky léků genetika MeSH
- genom rostlinný * MeSH
- jednonukleotidový polymorfismus MeSH
- mutace MeSH
- polyploidie * MeSH
- proteiny huseníčku genetika metabolismus MeSH
- půda chemie MeSH
- sekologanin-tryptaminové alkaloidy metabolismus MeSH
- vápníkové kanály metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- proteiny huseníčku MeSH
- půda MeSH
- sekologanin-tryptaminové alkaloidy MeSH
- serpentine (alkaloid) MeSH Prohlížeč
- TPC1 protein, Arabidopsis MeSH Prohlížeč
- vápníkové kanály MeSH
Parallel adaptation provides valuable insight into the predictability of evolutionary change through replicated natural experiments. A steadily increasing number of studies have demonstrated genomic parallelism, yet the magnitude of this parallelism varies depending on whether populations, species, or genera are compared. This led us to hypothesize that the magnitude of genomic parallelism scales with genetic divergence between lineages, but whether this is the case and the underlying evolutionary processes remain unknown. Here, we resequenced seven parallel lineages of two Arabidopsis species, which repeatedly adapted to challenging alpine environments. By combining genome-wide divergence scans with model-based approaches, we detected a suite of 151 genes that show parallel signatures of positive selection associated with alpine colonization, involved in response to cold, high radiation, short season, herbivores, and pathogens. We complemented these parallel candidates with published gene lists from five additional alpine Brassicaceae and tested our hypothesis on a broad scale spanning ∼0.02 to 18 My of divergence. Indeed, we found quantitatively variable genomic parallelism whose extent significantly decreased with increasing divergence between the compared lineages. We further modeled parallel evolution over the Arabidopsis candidate genes and showed that a decreasing probability of repeated selection on the same standing or introgressed alleles drives the observed pattern of divergence-dependent parallelism. We therefore conclude that genetic divergence between populations, species, and genera, affecting the pool of shared variants, is an important factor in the predictability of genome evolution.
- Klíčová slova
- Arabidopsis, alpine adaptation, evolution, genomics, parallelism,
- MeSH
- anotace sekvence MeSH
- Arabidopsis klasifikace genetika metabolismus účinky záření MeSH
- biologická evoluce * MeSH
- býložravci fyziologie MeSH
- fyziologická adaptace genetika MeSH
- fyziologický stres MeSH
- genetická variace * MeSH
- genetický drift MeSH
- genom rostlinný * MeSH
- genová introgrese MeSH
- genová ontologie MeSH
- ionizující záření MeSH
- modely genetické MeSH
- nízká teplota MeSH
- rostlinné proteiny genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- rostlinné proteiny MeSH
